Figure 13-57Spectrum of a High-Redshift Quasar The light from this quasar, known as PKS 2000-330, is so highly redshifted that spectral emission lines normally found in the far-ultraviolet (Lα and Lβ) are seen at visible wavelengths. Note the many deep absorption lines on the short-wavelength side of Lα. These lines, collectively called the Lyman-alpha forest, are believed to be created by remote clouds of gas along our line of sight to the quasar. Hydrogen in these clouds absorbs photons from the quasar at wavelengths less redshifted than the quasar’s Lα emission line.